Catalytic unit for solid fuel burning stoves

ABSTRACT

This invention describes a stove comprising a combustion chamber and a flue for removing exhaust from said combustion chamber, where said combustion chamber and said flue are connected via a passageway; said combustion chamber comprising a top and a bottom, where said top and said bottom are connected by one or more sides; a catalytic unit arranged between said combustion chamber and said flue in said passageway; said catalytic unit provides a guide way for the exhaust, where said catalytic unit comprises at least one isolating members and at least one catalytic member, said catalytic member comprising a first wave-like structure, said first wave-like structure being provided on at least one catalytic surface of said catalytic member and, in use, at least partly being in contact with the exhaust and, where, in use, the direction of the exhaust is substantially transverse to the waves of said first wave-like structure.

FIELD OF THE INVENTION

The present invention relates to a solid fuel burning stove comprising acatalytic unit.

BACKGROUND OF THE INVENTION

Wood and coal burning stoves are employed for home heating and purposessuch as cooking. However, especially the burning of wood often resultsin incomplete combustion and exhaust comprising a high amount ofparticles, volatile organic compounds and carbon monoxide, all of whichare a hazard to the environment.

Furthermore, the incomplete combustion results in a loss of overallcombustion efficiency.

In order to increase the combustion efficiency and minimize thepollution from the wood burning stove, the combustion temperature in thecombustion chamber has been increased, and catalytic convertersintroduced into the stove.

EP0037281 describes a wood burning stove with a combustion chamber and aflue, where a catalytic converter is located either in said combustionchamber or in the flue. The catalytic converter comprises a plurality ofcatalytic cells with a length oriented in the direction of the flow. Thecatalytic converter is a honeycomb structure with a plurality ofmutually parallel cells extending through the structure.

EP0354674 discloses a wood burning stove with a catalytic cell forreducing exhaust emissions from the stove. The catalytic cell forms asecondary combustion chamber within the stove communicating with theprimary combustion chamber. Hereby the exhaust from the primarycombustion chamber is catalytically combusted in the secondarycombustion chamber.

WO85/02455 discloses an insulated secondary combustion chamber where amixture of exhaust gasses from the primary combustion chamber is burned.The secondary combustion chamber can be retrofitted on existing woodburning stoves. The retrofitted apparatus is formed as a heat exchangerwith a first and second passageway, where the heat exchanger has anundulating shape for better heat exchange. Insulating material isprovided along one side of the first and second passageway,respectively. A perforated catalytic igniter is provided in the lowerportion.

However, in order to achieve the most powerful reduction of pollutantsfrom stoves, it is important to optimise the catalytic unit with regardto temperature and catalytic power.

Additionally, the catalytic unit is to be designed in a manner whichresults in a minimal pressure drop when the exhaust passes through thecatalytic unit. If the pressure drop is too large, the combustion in thecombustion chamber will be insufficient and result for example in alarge amount of particles.

OBJECT OF THE INVENTION

It is the object of the present invention to provide a stove having analternative catalytic unit for effectively minimising the exhaust ofparticles, carbon monoxide (CO) and volatile organic compounds (VOC),hereby increasing the overall combustion efficiency and decreasing thenegative effects on human health and the environment.

DESCRIPTION OF THE INVENTION

This object is achieved by a stove comprising

-   -   a combustion chamber and a flue for removing exhaust from said        combustion chamber, where said combustion chamber and said flue        are connected via a passageway;    -   said combustion chamber comprising a top and a bottom, where        said top and said bottom are connected by one or more sides;    -   a catalytic unit arranged between said combustion chamber and        said flue in said passageway;    -   said catalytic unit provides a guide way for the exhaust, where        said catalytic unit comprises at least two isolating members and        at least one catalytic member,    -   said catalytic member comprising a first wave-like structure,        said first wave-like structure being provided on at least one        catalytic surface of said catalytic member and, in use, at least        partly being in contact with the exhaust and, where, in use, the        direction of the exhaust is substantially transverse to the        waves of said first wave-like structure.

In one embodiment, the stove is a solid fuel burning stove. The solidfuel burning stove is to be understood as a stove capable of burning forexample wood and coal. The wood and coal are burned in a combustionchamber releasing exhaust, which is transported to the outside of abuilding by a flue. The exhaust is transported via a passageway from thecombustion chamber to the flue.

The passageway can be either just a connection or a secondary chamberfor heat exchange and/or secondary combustion of the particles presentin the exhaust. The passageway may also be a combination of both aconnection and a secondary chamber.

By “heat exchange” is meant that the heat from the exhaust istransmitted to the surroundings, whereby the temperature of the exhaustfrom the fuel is decreased.

The combustion chamber comprises a top and a bottom, which are connectedvia one or more sides. Solid fuel is arranged at the bottom of thecombustion chamber for burning. The exhaust obtained during burningexits the combustion chamber through an opening in the combustionchamber, preferable in the top or next to the top of the combustionchamber.

A catalytic unit is arranged in the passageway for boosting theoxidation of compounds in the exhaust from the combustion chamber.Hereby, the amount of particles, volatile organic compounds (VOCs) andcarbon monoxide (CO) is decreased in the exhaust.

In one embodiment, the catalytic unit is arranged just after thecombustion chamber, i.e. when the exhaust leaves the combustion chamber,it enters the catalytic unit. When the exhaust leaves the catalyticunit, it enters into the secondary chamber for maximal exploitation ofthe heat generated in both the combustion chamber and during thesecondary combustion in the catalytic unit. From the secondary chamber,the exhaust is directed to the flue. Thus, the catalytic unit provides aguide way for the exhaust on its way from the combustion chamber to theflue.

In one embodiment, the catalytic unit is arranged in the secondarychamber of the stove. A secondary chamber is commonly present inmultiple solid burning stoves, and the catalytic unit can be fitted intoexisting stoves without the necessity of redesigning presently knownstoves.

In a further embodiment, the catalytic unit forms the secondary chamberof the stove.

In one embodiment, the catalytic unit can be retrofitted onto existingstoves.

In another embodiment, the catalytic unit is installed in newly producedstoves. In one embodiment, the catalytic unit comprises a catalyticmember and at least two isolating members.

The catalytic member preferably operates at temperatures up to 1050° C.More preferably, the catalytic member operates at temperatures between200° C. to 900° C. In another preferred embodiment, the catalytic memberoperates at temperatures between 200 and 350° C.

In order to maintain the temperature of the exhaust after exiting thecombustion chamber, the catalytic unit further comprises at least oneisolating member. Hereby, the temperature is kept in a range between 200and 900° C.

By “at least one isolating member” is to be understood that the numberof isolating members enclosing the catalytic member can be one, two,three, four, five, six etc members.

More than one isolating member can be engaged with one another in orderto secure a high temperature close to the catalytic member and to form acatalytic unit, which forms a guide way for the exhaust.

In one embodiment, the guide way through the catalytic unit is a closedspace except for an inlet opening and an outlet opening.

At least an inlet opening and an outlet opening is present in thecatalytic unit for allowing the passage of exhaust into the catalyticunit and out of the catalytic unit. Hereby, the exhaust is able to comeinto contact with the catalytic surface of the catalytic member.Advantageously, the exhaust is able to come into contact with allcatalytic surfaces of the catalytic member.

In one embodiment, the inlet opening and the outlet opening is oneopening.

In one embodiment, the inlet opening is of a width similar to the widthof the passageway. In a further embodiment, the outlet opening is of awidth similar to the width of the passageway. In a further embodiment,the inlet opening and the outlet opening are of a width similar to thewidth of the passageway.

Isolating the catalytic unit along the flow direction of the exhaust byisolating members results in a minimal temperature loss over thecatalytic unit. Thus, an optimal reaction temperature with regard to thecatalytic process can be maintained i.e. between 200° C. and 900° C.Furthermore, a large pressure loss is prevented. Therefore, the exhausteasily exits the flue though the amount of particles, VOC and CO isdiminished.

The catalytic member is provided with a first wave-like structure on atleast one catalytic surface of the catalytic member.

As an example, the first wave-like structure can be a sinus-shaped curvehaving 5 cm between the first waves and a first wave-height of 1 cm.

In one embodiment, the distance between the first waves differs alongthe catalytic unit. In a further embodiment, the height of the firstwaves differs along the catalytic unit. In a still further embodiment,both the distance between the first waves and the height of the firstwaves differ along the catalytic unit.

The first wave-like structure is arranged in a manner, whereby theintended travel direction of the exhaust is directed substantiallytransverse to the first waves. Hereby, turbulence is induced in theexhaust flow and the exhaust flow is continuously mixed, whereby theentire flow comes into contact with the catalytic member. Furthermore,the catalytic area is increased.

The intended travel direction of the exhaust is to be understood as theprimary travel direction of the exhaust.

The design of the catalytic unit minimises the pressure drop between theair intake of the combustion chamber and the end of the flue.Preferably, the pressure drop over the catalytic unit is no differentfrom the pressure drop over the secondary combustion chamber notincluding a catalytic unit.

In one embodiment, the catalytic unit is designed in a manner whichallows a pressure drop between the combustion chamber and the end of theflue to be at a maximum of 12 Pa (static pressure) according to Europeanstandards (EN13240).

In one embodiment, the stove further comprises a blower in order toforce convection. In this embodiment, the design of the catalytic unitcan be more complex and hereby introduce a significant pressure drop.

The catalytic member can be arranged with regard to the isolatingmembers by either resting the catalytic member against the surface ofone of the isolating members or by small attaching means, where theattaching means are attached to both the catalytic member and to one ormore isolating members. By using the small attaching means, a givendistance between the isolating members and catalytic member can bemaintained.

In an advantageous embodiment, said catalytic member is integrated in anexposed isolating surface of at least one isolating member. Hereby, isto be understood, that the catalytic member is part of at least one ofthe isolating members and that the oxidative boosting takes place at asurface of the isolating member, where the surface is exposed to theexhaust passing through the catalytic unit.

The catalytic member can be integrated only partly on the exposedsurfaces of the isolating members. Hereby is to be understood that onlyparts of the exposed surface can be provided with the catalytic member.

By exposed isolating surface is to be understood the surface of theisolating member which faces the guide way for the exhaust and hereby isexposed at least partly to the exhaust passing through the catalyticunit.

In another embodiment, the catalytic member is only integrated with someof the exposed surfaces i.e. if the catalytic unit comprises twoisolating members and two exposed isolating surfaces, the catalyticmember is provided only on one of the exposed surfaces or if thecatalytic unit comprises four isolating members and four exposedisolating surfaces, the catalytic member is provided only on one, two orthree of the exposed surfaces.

In another embodiment, the catalytic member is integrated with all ofthe exposed isolating surfaces i.e. if the catalytic unit comprises twoisolating members and two exposed isolating surfaces, the catalyticmember is provided on both of the exposed isolating surfaces or if thecatalytic unit comprises four isolating members and four exposedisolating surfaces, the catalytic member is provided on four exposedisolating surfaces.

In one embodiment, the catalytic member is formed by adding a metalliclayer onto the exposed surface of the isolating member.

In an alternative embodiment, the exposed isolating surface is formed byproviding the surface with a ceramic layer and a catalytic metal layer.Hereby, the catalytic surface area is increased due to the porousstructure of the ceramic layer.

In a further advantageous embodiment, said catalytic unit comprises saidcatalytic member being surrounded by one isolating member.

In this embodiment, the isolating member is formed as a pipe or a tube,where the catalytic member can be arranged inside the tube. Since theisolating member is not to be assembled from more members the catalyticmember is easily installed in the stove. Furthermore, no assemblies willbe present and thus, the temperature of the catalytic unit can be keptat a high level to obtain optimal reduction of particles, VOC and CO.

Alternatively, the catalytic member can be an integrated part of theexposed surface of the isolating member.

In an advantageous embodiment, said exposed isolating surface of atleast one isolating member facing said catalytic member comprises asecond wave-like structure, where, in use, the direction of the exhaustis substantially transverse to the waves of said second wave-likestructure.

The at least one isolating member comprises at least one isolatingsurface. One of the isolating surfaces faces the catalytic member and isthus, an exposed isolating surface. Between this exposed isolatingsurface and the surface of the catalytic member, the flow of exhaustmoves.

The exposed isolating surface can comprise a second wave-like structure.

In one embodiment, the exposed isolating surface at least partlycomprises a second wave-like structure.

As an example, the second wave-like structure can be a sinus-shapedcurve having 5 cm between the second waves and a second wave-height of 1cm.

In one embodiment, the distance between the second waves differs alongthe catalytic unit. In a further embodiment, the height of the secondwaves differs along the catalytic unit. In a still further embodiment,both the distance between the second waves and the height of the secondwaves differs along the catalytic unit.

The second wave-like structure is arranged in a manner, whereby theintended travel direction of the exhaust is directed substantiallytransverse to the second waves. Hereby, further turbulence is induced inthe exhaust flow.

An increased number of collisions between CO, VOC, particles and oxygenat the surface of the catalytic member at a temperature between 200 and900° C. in combination with only a minor pressure drop over thecatalytic unit are obtained by providing the catalytic unit with bothfirst and second wave-like structures. The concentration of thepolluting components CO, VOC and particles are hereby efficientlydecreased.

In a further advantageous embodiment, the mutual distance perpendicularto the intended travel direction of the exhaust is constant between saidfirst and said second wave-like structures. Hereby, the flow of exhaustexperiences turbulence and an increased surface area of the catalyticmember along the flow path, but the pressure drop over the catalyticunit will only be minimal allowing an efficient flow of the exhaustthrough the catalytic unit and out the flue.

Arranging the catalytic member in the middle of the passageway willconstantly force the exhaust through the catalytic member. Hereby thenumber of collisions and the reduction of emissions will be increased byonly a minimal loss of pressure.

In a further advantageous embodiment, at least one isolating memberforms at least a part of the top of the combustion chamber.

One of the isolating members or a part of one of the isolating memberscan be a part of the general insulation of the combustion chamberespecially when the catalytic unit is arranged in direct connection tothe combustion chamber. Hereby, less material is to be used for optimalinsulation and combustion in the stove.

Furthermore, using an isolating member both as part of the combustionchamber as well as for the catalytic unit is less space demanding, whichis advantageous especially for small stoves.

In a further advantageous embodiment, said stove further comprises anadditional member, said additional member is arranged in saidpassageway, where said additional member extends said guide way for theexhaust and said additional member preferably is an additional isolatingmember.

Hereby, the travelling direction of the exhaust can be furtherrearranged in the passageway and an extended guide way through thepassageway is formed. Thus, the duration of the exhaust being in thepassageway is increased and hence the amount of particles, VOC and COdecreased.

In one embodiment, the additional member is made from isolatingmaterial. The isolating material can be the same as described below forthe isolating members of the catalytic unit. Hereby, the hightemperature between 200° C. and 900° C. of the exhaust is maintained andthe combustion of the particles, VOC and CO is increased.

In a further embodiment, the material of the additional member is thesame as for the isolating members.

In a further embodiment, said additional member is a plate-like member.

In a still further embodiment, the additional member is arranged in afirst inclined position in the passageway in relation to the bottom ofthe combustion chamber maintaining the exhaust in the passageway for alonger time either forcing the exhaust downwards or just modifying thenatural upwards movement of the exhaust.

The additional member can be arranged either before or after thecatalytic unit in the passageway with regard to the travel direction ofthe exhaust.

In one embodiment, the additional member is a part of the catalyticunit.

In a further advantageous embodiment, said at least one isolating membercomprises at least one end at at least one opening of the catalyticunit, where, in use, said exhaust enters and/or exits said catalyticunit and that at least one of said isolating member comprises a bentedge where the bent edge is formed at least partly along said at leastone end of said isolating member.

To allow the inlet and outlet of the exhaust the catalytic unit isprovided with at least one opening for the exhaust to enter into and outof the catalytic unit, the inlet and outlet opening, respectively.

In this embodiment, the at least one opening is provided at the end ofthe catalytic unit and thus, at the end of the at least one isolatingmember.

In one embodiment, the opening is both an inlet and an outlet openingfor the exhaust.

In one embodiment, the bent edge is shaped to direct the flow of theexhaust towards the catalytic member and is thus formed at the inletopening of the catalytic unit.

In one embodiment, the bent edge is arranged on the isolated memberopposite of the isolating member facing the combustion chamber, and thebent edge is arranged next to the inlet of the catalytic unit. Thus, thebent edge prevents the exhaust from not entering the guide way throughthe catalytic unit. Hence, the connection between the catalytic unit andthe combustion chamber is automatically generated by the bent edge.

Alternatively, the bent edge is formed at the outlet opening of thecatalytic unit to direct the exhaust properly towards the flue.

The bent edge can be formed along the entire end of the isolating memberor one or more bent edges can be formed along the end of the isolatingmember i.e. each bent edge only arranged along part of the end.

In a further advantageous embodiment, said catalytic member is a plate.

In a still further advantageous embodiment, the plate is arrangedbetween by at least two isolating members, where at least one isolatingmember is arranged on either side of the catalytic member. Hereby, athin catalytic unit can be achieved, which takes up only a minimalamount of space and still is provided with a large surface area.

Furthermore, a plate only introduces a minimal pressure drop across thecatalytic unit.

In one embodiment, the thickness of the plate is preferably between 0.1to 3 cm. In a further embodiment, the thickness of the plate ispreferably between 0.5 and 2 cm. In a still further embodiment, thethickness of the plate is approximately 1 cm. In a still furtherembodiment, the thickness of the plate is preferably between 0.01 and 3cm. In a still further embodiment, the thickness of the plate ispreferably between 0.05 and 1 cm. In a still further embodiment, thethickness of the plate is preferably between 0.1 and 0.2 cm.

In a further advantageous embodiment, said catalytic member is a grid.Hereby, the total surface area of the catalytic member is enlarged, andthereby the capacity of the catalytic member for promoting reduction ofparticles, VOC and CO.

The first wave-like structure of the catalytic member introducesturbulence. Hence, the flow of exhaust is, besides continuously mixingthe exhaust, also able to pass through the openings of the grid, ande.g. particles are thus capable of being transported by the exhaust onboth sides of the catalytic member as well as from one side to the otherside. Efficient contact is therefore established between the componentsof the exhausts and all surfaces of the grid.

Furthermore, introducing a grid as the catalytic member lowers thepressure drop across the catalytic unit.

In one embodiment, the grid is a plate.

Potentially the passage through the grid can be clogged up due to theparticles in the exhaust. However, having both the first and secondwave-like structures increases the turbulence of the exhaust to adegree, which reduces the risk of the grid being clogged up. Thus, thecatalytic effect of the catalytic member can be exploited continuouslywithout the risk of the grid clogging up whereby the catalytic effectwould decrease or the guide way clog up whereby the exhaust would not beable to exit the combustion chamber.

In a further advantageous embodiment, said catalytic member is arrangedbetween two isolating members. Hereby, is to be understood that thecatalytic unit comprises two isolating members and one catalytic member,where the catalytic member is arranged between the two isolatingmembers. In one embodiment, the isolating members are plate-likemembers, where the plate-like members comprises two ends each at theinlet and outlet opening of the catalytic unit, respectively. Theisolating members further comprise two sides each, connecting the endsof the isolating members. Each of the plate-like members is arranged oneither side of a catalytic member in the form of a plate i.e. thecatalytic member is sandwiched between the two isolating members.

Advantageously, the catalytic member is a plate and a grid.

In a further advantageous embodiment, said exposed isolating surface onsaid at least one isolating member comprises at least one protrudingportion.

By providing at least one protruding portion on the exposed isolatingsurface, a guide way is automatically created between isolating members.The size of the guide way can easily be changed by changing the size ofthe protruding portions. In one embodiment, the catalytic member isarranged in the guide way.

The top of the at least one protruding portion rests against the exposedisolating surface of the opposite arranged isolating member.Alternatively, the top of the at least one protruding portion arrangedat a first isolating member can rest against the top of anotherprotruding portion arranged at a second isolating member.

In a still further advantageous embodiment, said at least one isolatingmember comprises at least two ends at at least an inlet and an outletopening of said catalytic unit, where, in use, said exhaust enters andexits said catalytic unit, said at least two ends is connected by atleast two sides and where said at least one protruding portion isarranged along at least one of said sides of said isolating member.

To allow the inlet and outlet of the exhaust the catalytic unit isprovided with an inlet and an outlet opening, respectively. In thisembodiment, the at least one opening is provided at the end of thecatalytic unit and thus, at the end of the at least one isolatingmember. The ends of the isolating members are connected by isolatingsides to form the isolating member. Along at least part of the sidesprotruding portions can be provided.

A space will be formed between the isolating members when an isolatingmember engages with another isolating member for forming a catalyticunit if at least one side of one of the isolating members is providedwith protruding portions. The exhaust travels through this space whichforms a guide way for the exhaust.

In one embodiment, the catalytic unit comprises two isolating memberswhere both members comprise protruding portions. The protruding portionof the first isolating member and the protruding portion of the secondisolating member engage during the formation of a catalytic unit.Hereby, a space between the exposed isolating surfaces is created.

In one embodiment, the catalytic member can be retained betweenisolating members by being arranged between the protruding portions andhereby being retained in position within the catalytic unit.

In a further embodiment, the catalytic member is retained between theisolating members by being arranged between the protruding portions ofone of the isolating members and the surface of the other isolatingmember where the two isolating members engage.

In a further embodiment, the catalytic member is arranged in a recessformed along the sides of at least one of the isolating members. Hereby,the engagement between the isolating members is not influenced by thefact that part of the catalytic member is present where the isolatingmembers engage. Furthermore, the catalytic member is kept in place byengaging with the recess of the member.

In a further embodiment, the recess is provided in the at least oneprotruding portion in at least one of the isolating members.

In a further advantageous embodiment, said catalytic member is coatedwith at least one layer of metal; said metal is located on the surfaceof said catalytic member for reacting with particles in said exhaust. Ina still further advantageous embodiment, said metal is palladium,platinum, cerium, rhodium, zinc, cupper or a mixture hereof.

Hereby is to be understood that the catalytic member can comprise one,two, three, four etc. layers of metal.

In one embodiment, the layer of metal fully coats the catalytic member.

In a further embodiment, the layer of metal partly coats the catalyticmember.

By coating the entire surface of the catalytic member with at least onemetal layer, the catalysing compound will be distributed over the entiresurface of the catalytic member and will be as effective as possible.

The metal can be provided in combination with a ceramic monolith layer.The ceramic monolith is porous. Therefore, the ceramic monolith has ahigh surface area pr. volume upon which surface the metal can be coated.Hence, a large catalytic area can be obtained. Thus, using both ceramicmonolith and metal increases the catalytic activity of the catalyticmember.

In one embodiment, the catalytic member has a steel core, preferably ofstainless steel, where the steel core is coated with a ceramic monolithlayer comprising Al₂O₃ or SiO₂ and a metal layer.

In another embodiment, the catalytic member has a core of a ceramicmonolith layer comprising Al₂O₃ or SiO₂.

As a catalytic material can be used precious metals such as platinum,palladium, rhodium or metal oxides of one or more of the followingmetals: chromium, iron, molybdenum, wolfram, manganese, cobalt, copper,nickel, zinc.

In a further advantageous embodiment, said catalytic unit is inclinedrelative to said bottom of the combustion chamber. Thus, the catalyticunit is arranged in a second inclined position in the passagewaymaintaining the exhaust in the catalytic unit for a longer time, eitherforcing the exhaust downwards or just modifying the natural upwardsmovement of the exhaust. The catalytic unit is inclined with a givenangle relative to the bottom of the combustion chamber.

In a first embodiment, the angle is between 0-70°. In a secondembodiment, the angle is between 0-60°. In a third embodiment, the angleis between 0-45°. In a fourth embodiment, the angle is between 1-70°. Ina fifth embodiment, the angle is between 1-60°. In a sixth embodiment,the angle is between 1-45°. In a seventh embodiment, the angle isbetween 15-70°. In an eight embodiment, the angle is between 25-60°. Ina ninth embodiment, the angle is between 35-45°.

In a further advantageous embodiment, said catalytic unit is downwardlyinclined for forcing a downwardly movement of the exhaust. The freemovement of the exhaust is upwards due to the temperature of the exhaustamong other things. By forcing the direction of the exhaust to bedownwards in an inclined angle, the exhaust is forced to flow in adirection different from the free movement. Thus, the exhaust willmaintain in the catalytic unit for a longer time period whereby thesecondary combustion will be increased and fewer particles, VOC and COwill be directed to the environment.

In one embodiment, the catalytic unit and the additional member areinclined relative to the bottom of the combustion chamber having asubstantially similarly angle. Thus, the isolating members and theadditional member are substantially parallel.

In a further advantageous embodiment, said isolating members are made ofvermiculite. Vermiculite is a natural mineral that expands with theapplication of heat. Vermiculite is formed by weathering or hydrothermalalteration of biotite or phlogopite.

Vermiculite is a fire resistant material which can cope with hightemperatures without being damaged and which in addition shows highisolating properties and non-reactivity against contents in the exhaustfrom solid fuel burning stoves.

Alternatively, Calcium Silicate, Perlite and moler earth (diatomaceousearth) can be used for the isolating members. All of which are fireresistant material which can cope with high temperatures as describedfor Vermiculite. Furthermore, these materials along with Vermiculite areof an insulating nature resulting in the isolating member being aninsulating member as well. This further has the advantage that theexhaust travelling through the catalytic unit can be maintained in thehigh end of the temperature range. This results in combustionautomatically along with combustion due to the catalytic member and thesystem is kept adiabatic. Furthermore, it results in the temperaturerange between 200° C. and 900° C. can be kept for a longer time periodwhy the catalytic process can be maintained for a longer period of time.Thus, more efficient removal of CO, VOC and particles from the exhaustis achieved.

In a further advantageous embodiment, iron and iron alloys includingsteel, nickel, chromium, cobalt, molybdenum, titanium, wolfram, vanadiumand other temperature resistant metals can be used for the isolatingmembers as well as alloys comprising one or more of these metals. Theadvantages of these metals and the alloys to be used are that they cancope with high temperatures as well as they are relative easily shaped.

DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a first embodiment of a catalytic unit;

FIG. 2 illustrates a solid fuel burning stove comprising a firstembodiment of a catalytic unit;

FIG. 3 illustrates a close-up of the first embodiment of the catalyticunit as illustrated in FIG. 2;

FIG. 4 illustrates a solid fuel burning stove comprising a secondembodiment of a catalytic unit;

FIG. 5 illustrates a close-up of the second embodiment of the catalyticunit as illustrated in FIG. 4A;

FIG. 6 illustrates a solid fuel burning stove comprising a thirdembodiment of a catalytic unit;

FIG. 7 illustrates a fourth embodiment of a catalytic unit;

FIG. 8 illustrates a fifth embodiment of a catalytic unit.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a first embodiment of a catalytic unit 101 comprisinga catalytic member 103 and two isolating members 105.

The catalytic member 103 is shaped as a plate and comprises a firstwave-like structure 107.

The two isolating members 105 a,b are plate-like members and arearranged on either side of the catalytic member 103. The surface 104 a,bof the isolating members 105 a,b facing the catalytic member is providedwith a second wave-like structure 109 a,b. The two isolating memberseach comprise two ends 110 a,b,c,d and two sides 108 a,b,c,d.

Furthermore, one of the isolating members 105 b comprises a bent edge111 along the end of the isolating member 105 b. The bent edge 111secures the direction of the exhaust from the combustion chamber andinto the space 113 between the two isolating members 105 a,b asillustrated in FIG. 2. This isolating member 105 b further comprisesprotruding portions 106, which rests against the other isolating member105 a, when the isolating members 105 a,b are assembled to form acatalytic unit 101.

FIG. 2 illustrates a cross-section of a solid fuel burning stove 115comprising a first embodiment of a catalytic unit 101. The catalyticunit 101 is arranged in the passageway 118 between the combustionchamber 117 and the flue 119. In this illustration, the intended traveldirection of the exhaust 121 is shown for illustration purposes alone asa white band moving in the direction of the arrow. The exhaust 121enters the catalytic unit 101 through the inlet opening 112 and exitsthrough the outlet opening 114. For illustration purposes and in orderto illustrate the inlet opening 112 the right side of the stove isremoved in this figure.

The combustion chamber 117 comprises a top 123 and a bottom 122connected by sides 124.

The exhaust 121 travels from the combustion chamber 117 to the catalyticunit 101, where the bent edge 111 of the catalytic unit 101 prevents theexhaust 121 from moving further up and directs the exhaust 121 inbetween the isolating members 105 a,b for contact with the catalyticmember before the exhaust 121 exits the catalytic unit 101 and travelstowards the flue 119.

In this embodiment, one of the isolating members 105 a forms the top 123of the combustion chamber 117, as well as being an isolating member 105a of the catalytic unit 101.

A close-up of the first embodiment of the catalytic unit 101 in use isillustrated in FIG. 3 which is a close-up of the region defined by thecircle A defined in FIG. 2.

In this close-up, it is illustrated how the catalytic member 103 isarranged between the two isolating members 105 a,b, with the mutualdistance 125 being constant between the first wave-like structure 107and the second wave-like structure 109 a,b i.e. that the top of thefirst waves correlates with the top of the second waves.

Furthermore, it is illustrated how the two isolating members 105 a,bengage with one another at the sides of the catalytic unit 101 due tothe protruding portion 106 of one of the isolating members 105 b.

The close-up, furthermore, illustrates how the exhaust 121 is able topass between the catalytic member 103 and the isolating members 105 a,bon both sides of the catalytic member 10 i.e. both between the firstisolating member 105 a and the catalytic member 103 as well as betweenthe second isolating member 105 b and the catalytic member 103. Inaddition, the exhaust 121 is able to pass through the catalytic member103. The catalytic member 103 can for example be a grid.

FIG. 4 illustrates a cross-section of a solid fuel burning stove 215comprising a second embodiment of a catalytic unit 201. The catalyticunit 201 is arranged between the combustion chamber 217 and the flue219. In this illustration, the intended travel direction of the exhaust221 is shown for illustration purposes alone as a white band moving inthe direction of the arrow. For illustration purposes and in order toillustrate the inlet opening the right side of the stove is removed inthis figure.

The exhaust 221 travels from the combustion chamber 217 to the catalyticunit 201, where the bent edge 211 of the catalytic unit 201 prevents theexhaust 221 from moving further up and directs the exhaust 221 inbetween the isolating members 205 a,b for contact with the catalyticmember 203.

In this embodiment, an additional member 227 is arranged after thecatalytic unit 201 with regard to the travel direction of the exhaustforcing the exhaust 221 to travel in a space between the additionalmember 227 and one of the isolating members 205 b before the exhaust 221travels towards the flue 219.

Advantageously, the additional member 227 is an additional isolatingmember, in order to maintain a high temperature of the exhaust 221.Increasing the travelling path of the exhaust 221 through the catalyticunit 201 reduces the amount of particles CO and VOCs in the finalexhaust 221 leaving the stove 215.

In this embodiment, one of the isolating members 205 a forms the top 223of the combustion chamber 217, as well as being an isolating member 205a of the catalytic unit 201.

A close-up of the second embodiment of the catalytic unit 201 in use isillustrated in FIG. 5 which is a close-up of the region defined by thecircle B defined in FIG. 4.

In this close-up, it is illustrated how the catalytic member 203 isarranged between the two isolating members 205 a,b, with the mutualdistance 225 being constant between the first wave-like structure 207and the second wave-like structure 209 a,b, i.e. that the top of thefirst waves correlates with the top of the second waves.

The close-up illustrates how the exhaust 221 passes between thecatalytic member 203 and the isolating members 205 a,b. Furthermore, itis illustrated how the direction of the exhaust 221 is changed by theadditional member 227 in the passageway 218. Hereby, the time spent bythe exhaust 221 in the passageway 218 before it enters the flue isincreased. Thus, the amount of particles VOC and CO in the exhaust 221is reduced further before it exits the stove via the flue.

FIG. 6 illustrates a cross-section of a solid fuel burning stove 315comprising a third embodiment of a catalytic unit 301. The catalyticunit 301 is arranged between the combustion chamber 317 and the flue319. In this illustration, the intended travel direction of the exhaust321 is shown for illustration purposes alone as a white band moving inthe direction of the arrow.

In this embodiment, an additional member 327 is arranged in thepassageway 318, where the additional member 327 is part of the top 323of the combustion chamber 317. The exhaust 321 is forced downwards fromthe combustion chamber 317 between the additional member 327 and one ofthe isolating members 305 b, before it interacts with the catalyticmember 303 between the two isolating members 305 a,b of the catalyticunit 301 and enters into the flue 319.

One of the isolating members 305 b comprises a bent end 311. In thisembodiment, the bent end 311 directs the exhaust 321 out of thecatalytic unit 301 and towards the flue 319.

FIG. 7 illustrates a fourth embodiment of a catalytic unit 401comprising a catalytic member 403 and two isolating members 405 a,b.

The catalytic member 403 is integrated with the exposed isolatingsurface 404 a of one of the isolating members 405 a and comprises afirst wave-like structure.

In a further embodiment, a catalytic member 403 can be provided on theexposed isolating surface 404 b of the other isolating member 405 b aswell.

Furthermore, one of the isolating members 405 b comprises a bent edge411 along the end of the isolating member 405 b. The isolating member405 b further comprises protruding portions 406, which rests against theother isolating member 405 a, when the isolating members 405 a,b areassembled to form a catalytic unit 401.

FIG. 8 illustrates a fifth embodiment of a catalytic unit 501 comprisinga catalytic member 503 and one isolating member 505.

The catalytic member 503 is shaped as a plate and comprises a firstwave-like structure. The isolating member 505 surrounds the catalyticmember 503 but leaves an outlet and an inlet opening for the exhaust toenter and exit the catalytic unit 501.

1. A stove comprising a combustion chamber and a flue for removingexhaust from said combustion chamber (117), where said combustionchamber and said flue are connected via a passageway; said combustionchamber comprising a top and a bottom, where said top and said bottomare connected by one or more sides; a catalytic unit arranged betweensaid combustion chamber and said flue in said passageway; said catalyticunit provides a guide way for the exhaust, where said catalytic unitcomprises at least one isolating member and at least one catalyticmember, said catalytic member comprising a first wave-like structure,said first wave-like structure being provided on at least one catalyticsurface of said catalytic member and, in use, at least partly being incontact with the exhaust and, where, in use, the direction of theexhaust is substantially transverse to the waves of said first wave-likestructure.
 2. The stove according to claim 1 wherein said catalyticmember is integrated in an exposed isolating surface of at least oneisolating member.
 3. The stove according to claim 1 wherein said exposedisolating surface of at least one isolating member facing said catalyticmember comprise a second wave-like structure, where, in use, thedirection of the exhaust is substantially transverse to the waves ofsaid second wave-like structure.
 4. The stove according to claim 3wherein the mutual distance perpendicular to the intended traveldirection of the exhaust is constant between said first and said secondwave-like structures.
 5. The stove according to claim 1 wherein said atleast one isolating member forms at least a part of said top of thecombustion chamber.
 6. The stove according to claim 1 wherein said stovefurther comprises an additional member, said additional member isarranged in said passageway, where said additional member extends saidguide way for the exhaust and said additional member preferably is anadditional isolating member.
 7. The stove according to claim 1 whereinsaid at least one isolating member comprises at least one end at atleast one opening of the catalytic unit, where, in use, said exhaustenters and/or exits said catalytic unit and that at least one of saidisolating member comprises a bent edge where the bent edge is formed atleast partly along said at least one end of said isolating member. 8.The stove according to claim 1 wherein said catalytic member is a plate.9. The stove according to claim 1 wherein said catalytic member is agrid.
 10. The stove according to claim 1 wherein said catalytic unitcomprises two isolating members and one catalytic member, where saidcatalytic member is arranged between said two isolating members.
 11. Thestove according to claim 1 wherein said exposed isolating surface onsaid at least one isolating member comprises at least one protrudingportion.
 12. The stove according to claim 11 wherein said at least oneisolating member comprises at least two ends at at least an inlet and anoutlet opening of said catalytic unit, where, in use, said exhaustenters and exits said catalytic unit, said at least two ends isconnected by at least two sides and where said at least one protrudingportion is arranged along at least one of said sides of said isolatingmember.
 13. The stove according to claim 1 wherein said catalytic memberis coated with at least one layer of metal; said metal is located on thesurface of said catalytic member for reacting with carbon monoxide (CO),volatile organic compounds (VOC) and particles in said exhaust.
 14. Thestove according to claim 1 wherein said catalytic unit is inclinedrelative to said bottom of said combustion chamber.